The present invention relates to fastening devices for rigidly fastening one member in an adjusted position with respect to another, and it relates more particularly to means for locking such members rigidly together while allowing adjustment of the position of one of the members relative to the other prior to final tightening of the fastener.
There are numerous situations in which two members must be positioned relative to each other before they are rigidly, and in some cases permanently, locked together by means of a nut and bolt or similar fastening device. For example, in the construction of steel-frame buildings with masonry facings, it is common practice to provide continuous horizontal shelf angles at vertically spaced intervals up the walls, so that the brick wall or other masonry is supported by the steel frame-work. In such construction, erection of the steel frame-work precedes the masonry, with the masonry being brought up approximately to the level of the shelf angle where it is necessary to adjust the elevation of the shelf angle so that its horizontal leg will fall within the mortar joint between two courses of brick. Construction of the wall is then continued on top of the shelf angle. Additional shelf angles are provided as required by good engineering practice.
Due to inherent tolerances in the manufacture of steel framing, as well as in masonry construction, and due also to deflections that occur after the framework is erected, it is practically impossible to preset the shelf angles at their final locations until the wall is erected and structural loads are actually applied. Consequently, it is necessary to adjust the position of the shelf angle both vertically and horizontally with respect to a steel beam, or other structural member, to which it is attached, so that it is at the proper elevation relative to the brick courses above and below it.
Horizontal adjustment of the shelf angle is readily achieved simply by providing slots in a horizontal portion of one of the members so that the bolts can slide in the slots as the shelf angle is lined up with the brick wall. However, the use of vertical slots has not been considered satisfactory because of the necessity of locking the assembly against slippage due to gravity loads by means of a high-tensile bolt that requires the application of closely controlled tightening torque for generating sufficient friction between adjoining surfaces or by welding the assembly in its final position. Both these techniques require the use of specialized labor and equipment, which often are not at the site when the work is to be done. Furthermore, either of these prior techniques is time consuming and requires a high degree of quality control and inspection in order to ensure the desired results. Consequently, the typical installation relies on so-called "finger shims" which are slipped between the beam and the clips by which the shelf angle is attached. The shelf angle is thus raised or lowered by removing or inserting additional shims to achieve the desired elevation.
The use of such shims is very costly and time consuming due to the cost of the shims, the labor required to fit up and install them initially and the labor required to make the necessary adjustments in order to line up the shelf angle.
It is accordingly an object of the present invention not only to provide a simpler way to mount shelf angles on steel beams, but also to facilitate fastening any member rigidly to another while allowing for adjustment between such members prior to final locking of the assembly. Fastening means of the present invention are primarily intended for use in applications where the members to be fastened are normally subjected to external forces tending to shift them in one direction, the purpose of the invention being to positively lock such members together in such a way that friction between them is not relied upon to prevent slippage in that direction.